Transparent Conductive Structure, Device comprising the same, and the Manufacturing Method thereof

ABSTRACT

An optical electrical device comprises a base and a transparent conductive structure on the base is disclosed. The base further comprises a light-emitting device and the transparent conductive structure comprises a transparent conductive oxide layer and a passivation layer on the transparent conductive oxide layer. The material of the transparent conductive oxide layer comprises transparent conductive metal oxide, such as ZnO. Furthermore, the transparent conductive metal oxide also comprises impurities, such as a carrier e.g. gallium.

TECHNICAL FIELD

This present application relates to a device comprising a base and atransparent conductive structure on the base and the method ofmanufacturing thereof.

BACKGROUND OF THE DISCLOSURE

An optical electrical device such as light-emitting diode (LED) of thesolid-state lighting elements have the characteristics of low heatgeneration, long operational life and the light emitted by the LEDs hasa stable wavelength range so the LEDs have been widely used in variousapplications. Efforts have been devoted to the luminance of the LED inorder to apply the device to the lighting domain and further achieve thegoal of energy conservation and carbon reduction.

Many improvements on structures or materials to enhance the lightemitting efficiency of an LED have been realized. One of thoseimprovements is to add an enhanced film to increase light extraction,optic-electrical transition efficiency, contact resistance, forwardvoltage, or the like. However, the high temperature during manufacturingdamages the electrical and/or light properties of the enhanced film, andinduces the resistances of the enhanced films increasing and thewavelength of maximum transmittance shifting.

SUMMARY OF THE DISCLOSURE

An optical electrical device comprises a base and a transparentconductive structure on the base is disclosed. The base furthercomprises a light-emitting device which comprises a first semiconductorlayer, an active layer, and a second semiconductor layer. Thetransparent conductive structure comprises a transparent conductiveoxide layer and a passivation layer on the transparent conductive oxidelayer. The transparent conductive structure prevents carrierout-diffusion from the base. The material of the passivation layercomprises dielectric material, such as insulating oxide materialcomprising aluminum oxide and silicon oxide. The material of thetransparent conductive oxide layer comprises transparent conductivemetal oxide, such as ZnO. Furthermore, transparent conductive metaloxide also comprises impurities, such as a carrier e.g. gallium.

The present disclosure provides a manufacturing method of an opticalelectrical device comprises steps of providing a base and forming atransparent conductive structure on the base. The step of forming a basefurther comprises providing a substrate, forming semiconductor layers onthe substrate and growing an active layer located between thesemiconductor layers. The step of forming a transparent conductivestructure further comprises forming a transparent conductive oxide layeron the base and forming a passivation layer on the transparentconductive oxide layer. Moreover, an annealing process is applied afterthe base and the transparent conductive structure formed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an embodiment of a device having a transparent conductivelayer in accordance with the present disclosure;

FIGS. 2( a) and 2(b) depict the resistivity of the transparentconductive oxide layer with and without the passivation layer thereon ondifferent base related to the annealing temperature in various ambientin accordance with the present disclosure.

FIGS. 3( a) and 3(b) depict the impurity concentration of thetransparent conductive oxide layer with and without the passivationlayer thereon on different base related to the annealing temperature invarious ambient in accordance with the present disclosure.

FIGS. 4( a) and 4(b) depict the mobility of the element doped intransparent conductive oxide layer with and without the passivationlayer thereon on different base related to the annealing temperature invarious ambient in accordance with the present disclosure.

FIGS. 5( a)-5(b) depict the transmittance spectra of the transparentconductive oxide layer without the passivation layer thereon;

FIG. 5( c) depicts the transmittance spectra of the transparentconductive oxide layer with the passivation layer thereon related to thewavelength in various ambient in accordance with the present disclosure.

FIGS. 6( a)-6(d) show an embodiment of method for forming a device inaccordance with the present disclosure;

FIG. 7 shows an embodiment in accordance with the present disclosure.

FIG. 8 shows an embodiment in accordance with the present disclosure.

FIG. 9 shows an embodiment in accordance with the present disclosure.

DETAILED DESCRIPTION OF THE PRESENT DISCLOSURE

FIG. 1 shows a device 1 having a transparent conductive structure 105 inaccordance with an embodiment of the present disclosure. The device 1comprises a base 100 and a transparenet conductive structure 105 on thebase 100. The transparent conductive structure 105 comprises atransparent conductive oxide layer 106 on the base 100 and a passivationlayer 108 on the transparent conductive oxide layer 106. The passivationlayer 108 prevents a element doped in the transparent conductive oxidelayer 106 from diffusing outside the transparent conductive oxide layer106 by a thermal annealing process applied to the transparent conductivestructure 105. In other aspect, the passivation layer 108 prevents adoped element from being oxidizied by oxygen and further decreasing thedoping concentration of the doped element. The doped element is used toincrease conductivity of the transparent conductive oxide layer 106. Inother words, part of the doped element induces carriers, such aselectron, to improve conductivity of the transparent conductive oxidelayer 106. However, the concentration of the doped element is notdirectly corresponding to the concentration of the carrier induced bythe doped element. Since one doped element may induce one or moreelectrons and not all doped elements induce carriers, the concentrationof the carrier is related to the doping concentration. The base 100 canbe a substrate only or a substrate having a device structure thereon,wherein the device structure comprises passive and active components.The passive components comprises capacitors and resistors. The activecomponents comprises integrated-circuit structure andphotonic-electronic structure comprising a semiconductor light-emittingstructure, a semiconductor, a solar cell structure, or combinationthereof. The transparent conductive oxide layer 106 comprises metaloxide, such as zinc oxide(ZnO) doped with group IIIA element, e.g.aluminum-doped ZnO (AZO), gallium-doped ZnO (GZO), or indium-doped ZnO(IZO). Furthermore, the mole fraction of the group IIIA element doped isless than 10% of the transparent conductive oxide layer 106. In anembodiment, the mole fraction of the element doped is about 5%. In oneembodiment, the base 100 comprises a GaN-based light-emitting structure,and the transparent conductive oxide layer 106 comprises a ZnO-basedsemiconducting material having a band gap (−3.37 eV) wider than that ofGaN-based light-emitting structure and an exciton binding energy (−60meV) larger than that of GaN-based light-emitting structure. Theelectrical property of the transparent conductive oxide layer 106 isadjustable by controlling a doping concentration of the element doped inthe transparent conductive oxide layer 106. The passivation layer 108comprises a dielectric material, such as insulating oxide material, e.g.aluminum oxide or silicon oxide. The thickness of passivation layer isabout from 50 nm to 300 nm.

The method for manufacturing the device 1 comprises steps of providingthe base 100, depositing the transparent conductive oxide layer 106 onthe base 100, depositing the passivation layer 108 on the transparentconductive oxide layer 106, and performing a thermal annealing processto the device 1 for annealing the transparent conductive oxide layer 106in an annealing chamber. The method for depositing the transparentconductive oxide layer 106 comprises atomic layer deposition (ALD),chemical vapor deposition (CVD), sol-gel, or spray pyrolysis. Thethermal annealing process comprises rapid thermal annealing (RTA). Themethod for depositing the passivation layer 108 comprises e-beamcoating. In one embodiment, the base 100 comprises GaN-basedlight-emitting structure, the thermal annealing process is applied tothe device 1 for improving the ohmic contact between the interface ofthe transparent conductive oxide layer 106 and the GaN-basedlight-emitting structure. The light-emitting structure comprises ann-type semiconductor layer, a p-type semiconductor layer, and a activelayer configured to emit a incoherent light.

In one embodiment, the transparent conductive oxide layer 106 comprisingGa-doped ZnO is deposited on the base 100 by thermal-mode ALD with H₂Oas an oxidant source. Diethylzinc (DEZ) and triethylgallium (TEG) areused as the precursors for zinc and gallium, respectively, while H₂O isused as the precursor for oxygen or the oxidant source. Argon is used aspurge gas and carrier gas during the deposition. The depositiontemperature is 325° C. Precursors are sequentially injected with a pulseinto the reaction chamber with a carrier gas flow of 200 sccm at thebase pressure 0.2 torr. DEZ and H₂O are alternatively injected into thechamber for ZnO deposition, and the recipe for the deposition isrepeated in cycles. A few cycles of DEZ is replaced by TEG to dopegallium into ZnO with a ratio of Zn:Ga around 20:1. The method ofinjecting the precursors such as DEZ, TEG, and H₂O having an interval ofa pulsetime and a wait timekept at 0.02 secs and 10 secs. That is, theprecursors is injected following a loop of injecting 0.02 secs and stopfor 10 secs. The thickness of ALD-deposited transparent conductive oxidelayer 106 is between 100 nm and 500 nm.

The thermal annealing process comprising rapid thermal annealing (RTA)for annealing the transparent conductive oxide layer 106 is underconditions of an annealing time of 5 minutes, an annealing temperaturerange of 300-500° C. for the base 100 being a glass substrate and400-700° C. for the base 100 being a sapphire substrate. The electricalproperties of the transparent conductive oxide layer 108 arecharacterized by Hall method. Transmittance of the transparentconductive oxide layer 108 is measured by using a visiblespectrophotometer.

FIG. 2( a) shows the resistivity of the transparent conductive oxidelayer 106 comprising GZO with and without the passivation layer 108thereon on the base 100 which comprises a glass substrate annealed undervarious temperature and ambients. That is, different gases are used as acarrier gas in the annealing chamber including nitrogen, oxygen, or themixture of nitrogen and oxygen with a ratio of 4:1. The transparentconductive oxide layer 106 comprising GZO has a resistivity of 3.9×10⁻⁴Ω-cm. The thermal annealing process is found deleterious to theconductivity of the transparent conductive oxide layer 106. Theresistivity of the transparent conductive oxide layer 106 with thepassivation layer 108 thereon and annealed in the oxygen abmient or themixture ambient of nitrogen and oxygen is three orders of magnitudehigher than that of the transparent conductive oxide layer 106 withoutthe passivation layer 108 thereon. This evidence shows that no matterhow much the oxygen content is, the resistivity of the transparentconductive oxide layer increases during the thermal annealing processwith the oxygen ambient. In other words, the resistivity of thetransparent conductive oxide layer 106 deposited by ALD is sensitive tooxygen during annealing. Although the resistivity of the transparentconductive oxide layer 106 deposited on a glass substrate increases over1000 times after annealing in an oxygen ambient, the crystallinity ofthe transparent conductive oxide layer 106 do not show an obvious changeobserved from X-ray diffraction patterns. On the other hand, it is foundthat the resistivity of The transparent conductive oxide layer 106 canbe preserved by depositing the passivation layer 108 onto transparentconductive oxide layer 106. The transparent conductive oxide layer 106with the passivation layer 108 thereon has a resistivity lower than thatwithout the passivation layer 108 thereon after the thermal annealingprocess. The resistivity of the transparent conductive oxide layer 106with the passivation layer 108 thereon only slightly increases with theannealing temperature. Meanwhile, the transparent conductive oxide layer106 with the SiO₂ passivation layer 108 thereon exhibits a lowerresistivity of 8.2×10⁻⁴ Ω-cm than the transparent conductive oxide layer106 with the Al₂O₃ passivation layer of 1.4×10⁻³ Ω-cm after annealing at500° C. in nitrogen ambient. The transparent conductive oxide layer 106covered with the passivation layer 108 thereon can effectively avoid theincrease of resistivity. The resistivity of the transparent conductiveoxide layer 106 increases to 1.85×10⁻¹ Ω-cm while the carrier gas in theannealing chamber changes to 80% nitrogen and 20% oxygen filled in theannealing chamber. The resistivity of the transparent conductive oxidelayer 106 is increased after RTA, especially when oxygen is added intothe annealing chamber as the carrier gas. The increase of resistivity ofthe transparent conductive oxide layer 106 also increases the forwardoperating voltage of a light-emitting device while using the transparentconductive oxide layer 106 in a device structure comprising asemiconductor light-emitting structure. Thus the light emittingefficiency, which is luminous per watt, is decreased. To sum up, FIG. 2(a) shows the transparent conductive oxide layer 106 covered by thepassivation layer 108 composed of either silicon oxide or aluminum oxidemay reduce the increase of resistivity of the transparent conductiveoxide layer 106 after RTA.

FIG. 2( b) shows the resistivity of the transparent conductive oxidelayer 106 comprising GZO with and without the passivation layer 108thereon on the base 100 composed of a sapphire substrate under varioustemperature and ambients. That is, different gases are used as a carriergas in the annealing chamber including nitrogen and oxygen. Theresistivity of the transparent conductive oxide layer 106 deposited onthe sapphire substrate is 3.7×10⁻⁴ Ω-cm, which is lower than thatdeposited on the glass substrate. Similar to the trend of the embodimentin FIG. 2( a), the low resistivity of the transparent conductive oxidelayer 106 deposited on a sapphire substrate with a passivation layerthereon could be preserved even after RTA. The resistivity can bereduced to 3.3×10⁻⁴ Ω-cm capped by SiO₂ passivation layer and reduced to3.29×10⁻⁴ Ω-cm capped by Al₂O₃ passivation layer after 400° C. RTA. Theresistivity still keeps at 6.7×10⁻⁴ Ω-cm for the transparent conductiveoxide layer 106 capped by SiO₂ passivation layer annealed at 700° C.Moreover, it can be observed that the transparent conductive oxide layer106 has as low resistivity after the thermal annealing process as thatof the transparent conductive oxide layer 106 before the thermalannealing process. Similar to FIG. 2( a), the resistivity of thetransparent conductive oxide layer 106 formed on a sapphire substrate isalso increased after the thermal annealing process. In an embodiment,the increase of the resistivity also increases the forward operatingvoltage of a light-emitting device.

FIG. 3( a) shows the doped concentration of the doped element in thetransparent conductive oxide layer 106 with or without the passivationlayer thereon on the base 100 composed of a glass substrate undervarious temperature and ambients. That is, different gases are used as acarrier gas in the annealing chamber including nitrogen, oxygen, or themixture of nitrogen and oxygen with a ratio of 4:1. FIG. 3( b) show thedoped concentration of the doped element in the transparent conductiveoxide layer 106 with or without the passivation layer thereon on thebase 100 composed of a sapphire substrate under various temperature andambients. That is, different gases are used as a carrier gas in theannealing chamber including nitrogen and oxygen. In an embodiment, thedoped element in the transparent conductive oxide layer 106 inducescarrier, thus the carrier concentration is related to the concentrationof the doped element. The transparent conductive oxide layer 106comprising GZO has n-type conductivity and an electron concentration of10²¹ cm⁻³ from Hall measurements. As shown in FIG. 3( a), the dopedconcentration decays during the RTA, especially in oxygen ambient. It isattributed to the bonding of gallium donors in ZnO with oxygen and thebonding of oxygen vacancies with oxygen. That is the reason theresistivity of GZO is much sensitive when GZO is annealed in oxygenambient. When the transparent conductive oxide layer 106 is annealed innitrogen ambient, the doped concentration in the transparent conductiveoxide layer 106 also decays during annealing. It is suggested that zincis lost or evaporated during annealing, and causes oxygen contentincreasing and vacancy decreasing in the transparent conductive oxidelayer 106. Because of the increase of oxygen content in the transparentconductive oxide layer 106, the type of gallium oxide formed in thetransparent conductive oxide layer 106 changes from GaO (Ga atomssubstitute the Zn sites) to Ga₂O₃ due to the combination with oxygen.Then the concentration of doped element, i.e. Ga, for improvingconduction of the transparent conductive oxide layer 106 is reduced, andthe conduction mechanism during annealing in nitrogen ambient isdegraded. As the same trend, the transparent conductive oxide layer 106with a passivation layer 108 thereon keeps the doped concentrationconstant after annealing. It is suggested that the passivation layer 108prevents zinc in the GZO from evaporating during annealing. To be morespecific, no matter the transparent conductive oxide layer 106 is formedon a glass substrate depicted in FIG. 3( a) or a sapphire substratedepicted in FIG. 3( b), a passivation layer 108 comprising silicon oxideor aluminum oxide formed on the transparent conductive oxide layer 106can reduce the decrease of the doped concentration of the transparentconductive oxide layer 106 caused by RTA.

FIG. 4( a) illustrates the mobility of the doped element in thetransparent conductive oxide layer 106 comprising GZO with and withoutthe passivation layer deposited on the base 100 composed of a glasssubstrate under various temperature and an ambient. That is, nitrogen isused as a carrier gas in the annealing chamber. FIG. 4( b) illustratesthe mobility of the doped element in the transparent conductive oxidelayer 106 comprising GZO with and without the passivation layerdeposited on the base 100 composed of a sapphire substrate under varioustemperature and ambients. That is, different gases are used as a carriergas in the annealing chamber including nitrogen, oxygen, and the mixtureof nitrogen and oxygen with a ratio of 4:1. The doped elements in thetransparent conductive oxide layer 106 induces carriers thus themobility of the doped elements indicates the mobility of the carriers inthe transparent conductive oxide layer 106. The transparent conductiveoxide layer 106 comprising GZO has a mobity of about 16 cm²/V-sec.Reffering to FIGS. 4( a)-4(b), the mobility of GZO transparentconductive oxide layer 106 deposited on a glass substrate remains almostthe same value by capping the passivation layer 108 before and afterRTA. However, capping SiO₂ passivation layer provides better protectionthan capping Al₂O₃ passivation layer. Similar to the case of thetransparent conductive oxide layer 106 deposited on a glass substrate,the mobility of GZO deposited on the sapphire substrate is also enhancedwith a passivation layer thereon. For the transparent conductive oxidelayer 106 annealed at 700° C., the mobility keeps at 17.6 cm²/V-sec byAl₂O₃ passivation layer, and enhances to 30.2 cm²/V-sec by SiO₂passivation layer, as shown in FIG. 4( b). The mobility of thetransparent conductive oxide layer 106 deposited on the sapphiresubstrate is higher than that of the transparent conductive oxide layer106 deposited on the glass substrate, which is resulted from thesapphire substrate being crystal-oriented and thus improves the filmquality. To compared with the transparent conductive oxide layer 106formed on the base 100 composed of different materials in FIGS. 4( a)and 4(b), mobilities of the transparent conductive oxide layer 106 areall decreased after RTA though the amount of the decrease are differentdue to the different materials of the base 100. Besides, the passivationlayer 108 formed on the transparent conductive oxide layer 106 in FIGS.4( a) and 4(b) prevents the decrease of the mobility of the transparentconductive oxide layer 106 and increases the mobility of the transparentconductive oxide layer 106 under some circumstances after the thermalannealing process.

FIG. 5( a) shows the transmittance spectra of the transparent conductiveoxide layer 106 comprising GZO deposited on the base 100 composed of aglass substrate and annealed at various temperatures in the nitrogenambient. As shown in FIG. 5( a), the maximum transmittance of thetransparent conductive oxide layer 106 occurs at 92.9% at 455 nm and 89%at 710 nm, and the wavelength of the maximum transmittance shifts towardgreater wavelength (i.e. red-shift) and the intensity increases as theannealing temperature is increased. The transmittance increases in thelonger wavelength range which is different from the transmittancedecreasing in the longer wavelength range of the transparent conductiveoxide layer 106 without passivation formed above. Furthermore, thetransmittance is enhanced in the longer wavelength range after thethermal annealing process. The transmittance of wavelength at 900 nmraises from 84.4% to 84.9%, 91%, and 96.7% by the annealing temperatureof 300° C., 400° C., and 500° C., respectively. As shown in FIG. 5( a),the wavelength spectra of the transparent conductive oxide layer 106deposited on the base 100 composed of a glass substrate shifts after500° C. of RTA with nitrogen as a carrier gas in the annealing chamber.

FIG. 5( b) shows the transmittance spectra of the transparent conductiveoxide layer 106 deposited on the base 100 composed of a glass substrateand annealed at 500° C. in the various ambients. Similarily, the maximumtransmittance shifts to loger wavelength, i.e. red-shift, while moreoxygen flows to the annealing chamber. This suggests that the maximumtransmittance is dependent on the annealing temperature only, while thewavelength of maximum transmittance is dependent on the annealingtemperature and the ambient, i.e. the carrier gas in the annealingchamber. Refferring to FIG. 5( b), the transmittance of the transparentconductive oxide layer 106 larger than 95% is in a range of wavelengthbetween 450-550 nm. In comparison with the transmittance spectrachanging of the transparent conductive oxide layer 106 under differentRTA conditions, the composition of carrier gas affects the transmittancespectra and also causes the wavelength shift. To be more specific, moreoxygen added in the carrier gas induces more wavelength spectra shift ofthe transparent conductive oxide layer.

The wavelength of maximum transmittance in the blue or red range can bemodulated by controlling the thickness of the passivation layer as ananti-reflective coating layer. FIG. 5( c) shows the effects of theannealing temperature and ambient gas during the thermal annealingprocess on the transmittance spectra of the transparent conductive oxidelayer 106 comprising GZO with and without the passivation layer 108deposited on the base 100 composed of a glass substrate. The maximumtransmittance of the transparent conductive oxide layer 106 is 92.9% atwavelength of 455 nm and 89% at 710 nm before annealing. After thethermal annealing process, the maximum transmittance of the transparentconductive oxide layer 106 is not only kept in the fixed wavelengthrange but also enhanced in the blue and red ranges. The maximumtransmittance of the transparent conductive oxide layer 106 with thepassivation layer 108 is improved to 99.6% at wavelength of 659 nm whencapping a Al₂O₃ passivation layer and improved to 99.2% at wavelength of649 nm when capping a SiO₂ passivation layer, wherein the improvementsare at wavelengths in the red light range. Besides, the transmittance isimproved to 96.2% at 452 nm when capping a Al₂O₃ passivation layer, andimproved to 96.3% at 430 nm when capping a SiO₂ passivation layer,wherein the improvents are at wavelengths in the blue light range.Addition of the passivation layer and suitable annealing processsignificantly improve both the electrical and optical characteristics ofthe transparent conductive oxide layer, which are beneficial to theapplications for optoelectronic devices. To be more specific, FIG. 5( c)describes the transmittance spectra of the transparent conductive oxidelayer 106 with and without a passivation layer. FIG. 5( c) shows theincrease of the transmittance while the passivation layer is formed onthe transparent conductive oxide layer 106.

The disclosure presented above have demonstrated the effects of thepassivation layer and the thermal annealing process on the transparentconductive oxide layer comprising Ga-doped ZnO grown by thermal-ALD withusing H₂O as oxidant source. The transparent conductive oxide layer 106have the resistivity of 3.9×10⁻⁴ Ω-cm grown on a glass substrate and3.7×10⁻⁴ Ω-cm grown on a sapphire substrate. The resistivity andtransmittance of the transparent conductive oxide layer 106 increaseafter the thermal annealing process. The resistivity of the transparentconductive oxide layer is sensitive to oxygen during annealing, andincreases from 10⁻⁴ to 10⁻¹ Ω-cm during the thermal annealing process inthe oxygen ambient. Using aluminium oxide or silicon dioxide as apassivation layer on the transparent conductive oxide layer 106 is ableto preserve the low resistivity of ˜3.3×10⁻⁴ Ω-cm at a 400° C. RTAprocess. The maximum transmittance rises from 92.9% at 455 nm for thetransparent conductive oxide layer to 96.5% at 486 nm at a 500° C. RTAprocess in the nitrogen ambient. With the passivation layer, the maximumtransmittance of GZO would improve to ˜99% in red light range, and ˜96%in blue light range after the thermal annealing process. Addition of thepassivation layer and suitable annealing process would significantlyimprove both the electrical and optical characteristics of thetransparent conductive oxide layer, which are beneficial to theapplications for optoelectronic devices. With the disclosure presentedabove, the passivation layers used to preserve the optical andelectrical characteristics of the transparent conductive oxide layerdecay after annealing or even enhance the transmittance and mobility.Since the transparent conductive oxide layer is used as a lightextracting layer, it is suitable to apply the transparent conductivestructure to a light-emitting device to enhance the optical andelectrical characteristic.

FIGS. 6( a)-6(d) show an embodiment of a method for forming alight-emitting device 10 in accordance with one embodiment of thepresent disclosure. The method comprises steps of providing a substrate102 as shown in FIG. 6( a), epitaxially growing a first semiconductorlayer 1042 of a first conductivity-type on the substrate 102,epitaxially growing an active layer 1044 having multi-quantum wells onthe first semiconductor layer 1042 for emitting an incoherent light, andepitaxially growing a second semiconductor layer 1046 of a secondconductivity-type on the active layer 1044 to form a light-emittingstack 104 as shown in FIG. 6( b). The first semiconductor layer 1042 andthe second semiconductor layer 1046 has different conductivity types,e.g. the first semiconductor layer 1042 can be an n-type semiconductorlayer and the second semiconductor layer 1046 can be a p-typesemiconductor layer. A transparent conductive oxide layer 106 is thendeposited on the light-emitting stack 104 and a passivation layer 108 isthen formed on the transparent conductive oxide layer 106 as shown inthe FIG. 6( c). The method of manufacturing and the properties of thetransparent conductive oxide layer 106 and the passivation layer 108 areas the foregoing embodiments from FIG. 1 to FIG. 5( c). The method offorming the transparent conductive oxide layer 106 comprising providinga metal to form a metal oxide and providing an element as an impurityfor doping. The metal oxide comprises zinc oxide and the impuritycomprises gallium. Moreover, the step of forming the transparentconductive oxide layer 106 comprises changing the concentration of thegas injected during forming the transparent conductive oxide layer 106.To be more specific, injecting the impurity at a first concentrationinto the the transparent conductive oxide layer 106 while forming afirst portion of the the transparent conductive oxide layer 106 andinjecting the impurity at a second concentration into the thetransparent conductive oxide layer 106 while forming a second portion ofthe the transparent conductive oxide layer 106. Besides, a concentrationratio between the impurity provided and the metal of the metal oxideprovided to form transparent conductive oxide layer 106 is larger than3%. To be more specific, the ratio is between 5%-20%.

Referring to the FIG. 6( d), a recess 114 is formed in the passivationlayer 108 to expose a part of the transparent conductive oxide layer106, and a first electrode pad 110 is then formed on the exposedtransparent conductive oxide layer 106. A second electrode pad 112 isformed on a side of the substrate 102 oppossing to the light-emittingstack 104. A thermal annealing process is performed on thelight-emitting device 10, and a vertical-type light-emitting device asshown in FIG. 6( d) is formed. In another embodiment, the thermalannealing process is performed after the passivation layer 108 is formedand before forming the electrode pad is formed. The detail of thethermal annealing process are disclosed as the foregoing embodimentsfrom FIG. 1 to FIG. 5( c). FIG. 7 shows a horizontal-type light-emittingdevice 11 in accordance with an embodiment of this application. Thelight-emitting stack 104 is etched to exposed a part of the firstsemiconductor layer 1042, and the second electrode pad 112 is formed onthe exposed part of the first semiconductor layer 1042.

In another embodiment, a transparent conductive layer is adopted toenhance the conductivity. Referring to FIG. 8, the light emitting device20 comprises a first semiconductor layer 2042 of a firstconductivity-type on the substrate 202, an active layer 2044 on thefirst semiconductor layer 2042 for emitting an incoherent light, and asecond semiconductor layer 2046 of a second conductivity-type on theactive layer 2044 to form a light-emitting stack 204. The firstsemiconductor layer 2042 and the second semiconductor layer 2046 hasdifferent conductivity type, e.g. the first semiconductor layer 2042 canbe an n-type semiconductor layer and the second semiconductor layer 2046can be a p-type semiconductor layer. The transparent conductive layer205 is formed on the second semiconductor layer 2046 and the material ofthe transparent conductive layer 205 comprises indium tin oxide (ITO).The ITO used in the transparent conductive layer 205 compriss a tin oftetravalent state and an indium of trivalent state, and the molefraction of the tin is less than 15%. In another embodiment, the molefraction of tin in ITO is between 1%-10%. The two metal elements used inthe transparent conductive layer 205 are of different valence state. Tobe more specific, tin is an element of the group IVA and indium is anelement of group IIIA wherein the two different groups are next to eachother. A transparent conductive oxide layer 206 is formed on thetransparent conductive layer 205 and a passivation layer 208 is formedon the transparent conductive oxide layer 206. In this embodiment, thematerial of the transparent conductive oxide layer 206 comprises GZO.The GZO used in the transparent conductive oxide layer 206 comprises azinc of bivalent state and a gallium of trivalent state, and the molefraction of the gallium is less than 10%. In an embodiment, theconcentration of the gallium can be 1%-5%. The two metal elements usedin the transparent conductive oxide layer 206 are of different valencestate. To be more specific, zinc is an element of the group IIB andgallium is an element of group IIIA wherein the two different groups arenext to each other. In comparison with the transparent conductive layer205 and the transparent conductive oxide layer 206, the two layerscomprise metal elements of a group (indium of the transparent conductivelayer 205 and gallium of the transparent conductive oxide layer 206) andmetal elements have different valence state (tin of tetravalent state inthe transparent conductive layer 205 and zinc of bivalent state in thetransparent conductive oxide layer 206). A recess 214 is formed in thepassivation layer 208 to expose a part of the transparent conductiveoxide layer 206, and a first electrode pad 210 is then formed on theexposed transparent conductive oxide layer 206. A second electrode 212is formed on a side of the substrate 202 opposing to the light-emittingstack 204.

Referring to FIG. 9, a horizontal-type light-emitting device 21 inaccordance with one embodiment of the present disclosure comprises asubstrate 202, a light-emitting stack 204, a transparent conductivelayer 205, a transparent conductive oxide layer 206, a passivation layer208, a first electrode pad 210 and a second electrode pad 212. Thelight-emitting stack 204 comprises a first semiconductor layer 2042, anactive layer 2044, and a second semiconductor layer 2046. In thisembodiment, the light-emitting stack 204 is etched to expose a part ofthe first semiconductor layer 2042 wherein the second electrode pad 212is formed on the exposed part of the first semiconductor layer 2042.Moreover, the second semiconductor layer 2046 is etched to form aplurality of hexagonal-pyramid cavities 2052. Thus, convexs and concavesare formed on the top surface 2051 of the second semiconductor layer2046. Besides, the hexagonal-pyramid cavities 2052 are extended downwardfrom the top surface 2051 so each of the transparent conductive layer205 formed on the second semiconductor layer 2046 and the transparentconductive oxide layer 206 formed on the transparent conductive layer205 has a concave-convex surface. A recess 214 is formed in thepassivation layer 108 to expose a part of the transparent conductiveoxide layer 206, and a first electrode pad 210 is then formed on theexposed part of the transparent conductive oxide layer 206.

It will be apparent to those having ordinary skill in the art thatvarious modifications and variations can be made to the devices inaccordance with the present disclosure without departing from the scopeor spirit of the disclosure. In view of the foregoing, it is intendedthat the present disclosure covers modifications and variations of thisdisclosure provided they fall within the scope of the following claimsand their equivalents.

What is claimed is:
 1. An optical electrical device, comprising: a base;a first transparent conductive layer comprising a first metal oxidehaving a first metal element and a fourth metal element on the base; asecond transparent conductive layer comprising a second metal oxidehaving a second metal element and a third metal element on the firsttransparent conductive layer; and a passivation layer comprising adielectric material on the second transparent conductive layer, whereinthe first metal element is different from the second element.
 2. Theoptical electrical device to claim 1, wherein a mole fraction of thefourth metal element is greater than that of the first metal element inthe first metal oxide.
 3. The optical electrical device to claim 1,wherein a mole fraction of the second metal element is greater than thatof the third metal element in the second metal oxide.
 4. The opticalelectrical device to claim 1, wherein a mole fraction of the first metalelement in the first metal oxide is less than 15%.
 5. The opticalelectrical device to claim 1, wherein a valence state of the first metalelement is different from that of the second metal element.
 6. Theoptical electrical device to claim 1, wherein a valence state differencebetween the first metal element and the second metal element is two. 7.The optical electrical device to claim 6, wherein the first metal is ingroup IVA.
 8. The optical electrical device to claim 1, wherein thesecond metal element and the third metal element belong to groupsdirectly next to each other in a standard periodic table.
 9. The opticalelectrical device to claim 1, wherein the third metal element istrivalent.
 10. The optical electrical device to claim 1, wherein thethird metal element and the fourth metal element are different elementsof a same group in a standard periodic table.
 11. The optical electricaldevice to claim 10, wherein the same group is group IIIA.
 12. Theoptical electrical device to claim 1, wherein a mole fraction of thethird metal element in the second metal oxide is less than 10%.
 13. Theoptical electrical device to claim 1, wherein the dielectric materialcomprises aluminum oxide or silicon oxide.
 14. The optical electricaldevice to claim 1, wherein resistivities of the first transparentconductive layer and the second transparent conductive layer are bothless than 3.3×10⁻⁴ Ω-cm.
 15. The optical electrical device to claim 1,wherein the base comprises a light-emitting semiconductor stackconfigured to emit an incoherent light, wherein the light-emittingsemiconductor stack comprises an n-type semiconductor layer, a p-typesemiconductor layer, and an active layer between the n-typesemiconductor layer and the p-type semiconductor layer.
 16. The opticalelectrical device to claim 15, wherein the p-type semiconductor layercomprises a plurality of hexagonal-pyramid cavities.
 17. The opticalelectrical device to claim 1, wherein a transmittance of the secondtransparent conductive layer is larger than 95% for a light with adominant wavelength between 450 nm and 550 nm.
 18. The opticalelectrical device to claim 1, further comprising a recess formed in thepassivation layer.
 19. The optical electrical device to claim 18,further comprising an electrode pad formed in the recess.
 20. Theoptical electrical device to claim 1, wherein a mole fraction of thefirst metal element in the first metal oxide is larger than that of thethird metal element in the second metal oxide.